MnO₂ + 4HCl = MnCl₂ + Cl₂ + 2H₂O
Cl₂ + H₂ = 2HCl
2HCl + Fe = FeCl₂ + H₂
FeCl₂ + 2KOH = Fe(OH)₂ + 2KCl
Fe²⁺ + 2Cl⁻ + 2K⁺ + 2OH⁻ = Fe(OH)₂↓ + 2K⁺ + 2Cl⁻
Fe²⁺ + 2OH⁻ = Fe(OH)₂↓
4Fe(OH)₂ + O₂ + 2H₂O = 4Fe(OH)₃
Fe(OH)₃ + 3HCl = FeCl₃ + 3H₂O
Fe(OH)₃↓ + 3H⁺ + 3Cl⁻ = Fe³⁺ + 3Cl⁻ + 3H₂O
Fe(OH)₃↓ + 3H⁺ = Fe³⁺ + 3H₂O